This invention relates to a signal processing device for processing signals.
1. Description of the Related Art
Devices for recording and reproducing, as necessary, image signals on and from magnetic tapes, magnetic discs, optical discs, etc. have become popular. Meanwhile, arrangements have been proposed for transmitting image signals reproduced by such devices to remote places or to other devices for varied purposes.
The image transmission system to be used for such purposes tends to have a drop-out of the signal being transmitted in each of different transmission stages including a transmitting system, a transmission line and a receiving system. It is, therefore, necessary to keep the transmitted signal at a high degree of quality by minimizing the drop-outs of the signal.
However, a reproduction circuit, particularly a reproducing head part thereof, which is included in the transmitting system often has fine dust causing signal drop-outs depending on the environment in which it operates. As a result, compared with an image signal recorded on a recording medium, an image signal temporarily stored at a frame memory or field memory which is employed as a buffer memory for transmission tends to have a greater amount of drop-out. In view of this, there has been developed contrived a method of confirming the contents of the buffer memory through a display made by a monitor device. This method however, necessitates use of a monitor device which must be above a certain quality level. The method is thus not desirable in terms of simplification and reduction in weight of the system. Besides, with the recording image quality increased, the observation of the display by human sight comes to a drop-out confirmable limit.
This problem not only exists in the above stated image transmission system but also generally exists in signal processing systems arranged to store image signals in memories.